Sonographic measures of the gluteus medius, gluteus minimus, and vastus medialis muscles.

Abstract

Intrarater, repeated-measures, within-session reliability study. To describe a standardized method and preliminary reliability estimates for sonographic measures of resting and contracted gluteus medius (GMd), gluteus minimus (GMn), and resting vastus medialis (VM) muscles. Sonography has been used to assess the morphology of a diversity of muscles in relation to a variety of musculoskeletal dysfunctions. Although the GMd, GMn, and VM muscles are associated with dysfunctions such as patellofemoral pain and osteoarthritis, there is a paucity of information regarding protocols for sonographic measurements of these muscles. A standardized method was developed and used to gather sonographic measures of resting and contracted (sidelying hip abduction task) GMd and GMn thickness and resting VM cross-sectional area during 1 measurement session in 29 female soccer players 14 to 17 years of age. Intrarater reliability values for ultrasound imaging measurements of resting, contracted, and change during contraction (intraclass correlation coefficient model 3,3 [ICC3,3]) of the GMd were 0.98 (95% confidence interval [CI]: 0.97, 0.99), 0.98 (95% CI: 0.96, 0.99), and 0.84 (95% CI: 0.71, 0.92), respectively, and of the GMn were 0.98 (95% CI: 0.97, 0.99), 0.94 (95% CI: 0.88, 0.97), and 0.53 (95% CI: 0.21, 0.76), respectively. Reliability (ICC3,3) for resting VM cross-sectional area was 0.99 (95% CI: 0.99, 0.99). Standard error of measurement for GMd, GMn, and VM varied between 0.5 and 1.6 mm, 0.3 and 1.4 mm, and 0.4 cm2, respectively, and 95% minimal detectable change ranged from 0.8 to 4.5 mm for the gluteals and 0.4 to 0.5 cm2 for the VM. Reliable sonographic measurements of the lateral hip and knee musculature at rest and during contraction are feasible. Further investigation is required to establish the generalizability and reproducibility of the protocols presented in this report.